1. Field of the Invention
Embodiments described herein generally relate to a magnetic recording device for recording/reproducing data using the magnetization state of a recording medium. More specifically, embodiments described herein relate to a tapered write head for microwave assisted magnetic recording (MAMR).
2. Description of the Related Art
The heart of a computer is a magnetic disk drive which typically includes a rotating magnetic disk, a slider that has read and write heads, a suspension arm above the rotating disk and an actuator arm that swings the suspension arm to place the read and/or write heads over selected circular tracks on the rotating disk. The suspension arm biases the slider into contact with the surface of the disk when the disk is not rotating but, when the disk rotates, air is swirled by the rotating disk adjacent an air bearing surface (ABS) of the slider causing the slider to ride on an air bearing a slight distance from the surface of the rotating disk. When the slider rides on the air bearing, the write and read heads are employed for writing magnetic impressions to and reading magnetic signal fields from the rotating disk. The read and write heads are connected to processing circuitry that operates according to a computer program to implement the writing and reading functions.
In recent years, the data recording density of magnetic recording devices has continued to increase and the size of 1 bit of a magnetic recording mark for recording to a magnetic medium continues to become smaller. When the magnetic recording density exceeds about 1 Tera bit per square inch (Tbpsi), there is a risk of data recorded to a magnetic recording medium being erased at room temperature due to the effects of heat fluctuation. In order to prevent data from being erased by the effect of heat fluctuation, it is generally necessary to raise the coercive force of the magnetic recording medium. However, there is a limit to the amount of magnetic flux released by a magnetic recording head from recording data by magnetization reversal of a magnetic recording medium.
Measures for solving the above referenced problem have recently focused on assisted recording systems for recording data in conjunction with other technology. One such measure that has been proposed to achieve a high recording density is a method in which a MAMR head is utilized. A high frequency magnetic field is applied to recording bits in a magnetic recording medium in order to weaken the coercive force of the recording bits. In this method, data may be recorded using a conventional magnetic recording head. A MAMR enabled magnetic recording head utilizes a spin torque oscillator (STO) for generating a microwave (high frequency AC magnetic field). Typically the STO may include a field generation layer (FGL) for generating an AC magnetic field, a spacer layer, and a spin polarization layer (SPL) for transmitting spin polarized torque. When the magnetic field from the write head is applied and current is conducted to the STO, the STO oscillates and may provide an AC magnetic field to the medium. The AC magnetic field may reduce the coercive force of the recording medium, thus high quality recording by MAMR may be achieved.
A MAMR head provides an effective assistance effect that enables a high recording density by virtue of the fact that an oscillator for generating a high frequency magnetic field is provided at a position of a main pole where the field intensity and magnetic field gradient are highest in the region of the ABS. In order to write data to the magnetic recording medium, in conjunction with the main pole of the magnetic head, the magnetic field may be concentrated on the magnetic recording medium. However, the main pole and the oscillator which are formed in different production processes are likely to have characteristic variations due to misalignment. The misalignment may reduce reliability of the MAMR head.
Therefore, there is a need in the art for an apparatus having a properly aligned main pole and oscillator in an MAMR head. Further, there is a need in the art for methods of forming an aligned main pole and oscillator in an MAMR head.